In 2010 we guessed our weight to be around 110lbs. Never could get it on a scale.
Showed up to the WPI regional and weighed in at 142
Spent the first hours of practice day changing the wheels and drivetrain and cutting everything off. Then measured the frame. It was out of square by 1/4", and wouldn't fit in the box. Spent the rest of the day shortening the frame bu cutting sections out by hand with a hacksaw and re-assembling the robot.
We learned a valuable lesson about being 2" under frame size and ALWAYS weight your bot _before_ showing up to a regional.